Published: 08/01/2014
Published: 08/01/2014
“The Logic behind placing the ATC LITE† system on the rig was to deal with the excess slops that have been experienced in the past on other drilling operations. Another factor was the need to reduce the time required to clean the tanks so that it did not fall into the critical path of operations. With the specifically placed wash heads, all tanks were cleaned in a timely fashion and resulted in a minimum amount of confined space man-hours. The ending results were very impressive.”
Ivan Dujmovic, M-I SWACO
“Our two main goals were reached: Reduced confine space entry and elimination of large amounts of wash water”
Repsol Sinopec Brazil
| Well Information | |
|---|---|
| Well Information Location | Offshore Brazil |
| Well Information Fluid Volume | RHELIANT† drilling fluid system |
| Well Information Tanks Cleaned | 28 |
| Well Information Time Period | 16 days |
| Well Information Water Usage | 80 bbls |
| Well Information Waste Removed | 1,360 bbls |
| Well Information Cleaning Time | 119 hours |
| Well Information CSE | 6 hours |
| Well Information Tank Cleaning Product | 520 liters |
In order to deal with excess slops and reduce the time required to clean tanks, Repsol Sinopec Brazil requested that M-I SWACO, a Schlumberger company, provide its ATC LITE system to Ocean Rig for deployment on Ocean Rig Mylos. Traditional cleaning method involved manual labor with extensive confined space entry and exposure to fluids and vapors. Additionally, high volumes of water usage generated additional waste and increased the costs of transportation and final disposal. Traditional cleaning methods raises many QHSE concerns about exposure time in confined spaces and in addition is very time consuming which results in costly delays.
ATC LITE technology provided a solution to reduce CSE, tank cleaning time, and waste generated from tank cleaning operations. M-I SWACO provided an automatic tank cleaning system composed of one ATC LITE system with strategically placed tank cleaning machines inside each tank and two slop pumps to return the wash water to the ATC LITE system for recycling and continuous use. The new technology is an improvement on the slow, labor-intensive, dirty and potentially dangerous tank cleaning task. ATC LITE technology is completely automated and designed to reduce cleaning time and waste generation, and minimize waste generation, and to reduce or eliminate entry into confined spaces.
Upon deployment, the ATC LITE System:
The tight hole drilling operation utilized the RHELIANT drilling fluid system. A total of 28 tanks were cleaned over a 16-day period using 80 bbls of water removing 1,360 bbls of solids and slop. TCM’s were permanently installed in each of the tanks; the tanks were sequentially cleaned and the total cleaning time was 119 hrs with only 6 hrs of CSE. Tank cleaning product usage was 520 liters. Each TCM circulates approximately 62.8 bbls/hr. Water usage and waste generation without ATC LITE technology would have been around 22,420 bbls of water with same amount of sludge/solids removed.
Previous cleaning of some of the mud tanks was done successfully, but this marked the first time the ATC LITE system was employed to clean all tanks after the completion of the SBM phase of the drilling campaign. M-I SWACO was able successfully to address QHSE issues concerning employee safety and Brazil’s environmental regulations. Through the use of this technology, tank cleaning required little water and resulted in minimal amounts of wash fluids for disposal, thus having a positive impact on the client’s economics. This first operation utilizing the ATC LITE system will serve as a benchmark for similar operations in the future.
Challenge: Pit cleaning onboard the Ocean Nomad has been a labor intensive task that has been carried out using the M-I SWACO 100-HP vacuum. This system is time consuming, produces unnecessary amounts of waste and raises many quality, health, safety and environmental (QHSE) concerns due to the time exposed to confined spaces. The job is made more difficult by the multi-low-level pipe work layout of the pits, creating obstructions for pit cleaning.
Solution: The M-I SWACO ATC unit was provided as the solution for improving the older pit cleaning processes on the Ocean Nomad. The unit was installed on the starboard mid-ship deck and hoses were run under the skip station, through the pump room and into the pit room. As this was a trial project, no deck penetrations were cut. To install the tank cleaning machines (TCMs) in their optimum positions, a temporary solution was found using pre-fabricated brackets to ensure optimal placement. Each pit was cleaned using one SC30 TCM and one Cloud 180 TCM. This setup gave between 80 to 90% coverage in each pit.
Results: The ATC unit cleaned 5 of the 7 pits onboard; each pit was cleaned to between 80 and 90% brine spec with the remaining mud/barite being removed using the vacuum and squeegees. No manual digging of barite or heavy solids was required. This was necessary due to the tank design on the rig. Pit entry was reduced to no more than 2 hr per pit with the total setup and cleaning time being no more than 5 hr per pit. Waste from the total cleanup was reduced to 12 skips containing 45 tons; however, this included 3 skips that were full of mud from the sand traps and also water that was generated during the manual cleaning of the slops pit and sand traps.
